Previously known cylindrical balers generally include a rear bale discharge gate pivotally mounted to a front portion of the baler frame. A bale is discharged from such a machine by pivoting the discharge gate rearwardly and upwardly permitting the bale to drop directly onto the ground or by first pivoting the discharge gate upwardly and rearwardly and then activating a lower conveyor on which the bale rests during formation in the bale forming chamber of the baler. The lower conveyor urges the bale rearwardly out of the machine and onto the ground. With both designs, the bale generally comes to rest underneath the discharge gate. According to one commonly used method for operating such cylindrical balers, after the bale has been discharged, the operator pulls forward a short distance so that the discharge gate may be closed without hitting the discharged bale. In order to be able to pull forward without disturbing the windrow in front of the baler and possibly over feeding the baler when the baling operation is resumed, the operator must backup a few meters before discharging a bale. This is a tedious and time consuming procedure. If it is not executed properly, there is a possibility that the gate, when closed, may rest on top of the bale. This may damage the baler or even cause it to turn over.
Several solutions have been proposed to simplify the procedure for discharge of cylindrical bales. For example, in U.S. Pat. No. 4,206,587, a cylindrical baler with a resiliently mounted transverse bar for rearwardly propelling a bale as it is discharged from the chamber of the baler is disclosed. With the action of the resiliently mounted bar, the bale is propelled with sufficient force to roll the bale rearwardly of the baler a sufficient distance so that the discharge gate of the baler may be closed without moving the baler forwardly. Also, in U.S. Pat. Nos. 4,208,862 and 4,218,866 a cylindrical baler with a bale forming chamber defined by plurality of reversably driven chains is disclosed. The chains are driven in a first direction during the bale forming operation and then are automatically reversably driven during the bale discharge operation to impart a rearwardly directed top spin to the bale as it is discharged from the bale forming chamber. The top spin carries the bale away from the baler a sufficient distance so that the baler does not have to be driven forwardly to permit the closing of the discharge gate. Both of these approaches present certain inherent disadvantages. Both approaches provide a rearwardly directed top spin to the bale as it is discharged from the bale forming chamber. The rearward motion of the bale is uncontrolled. If the baling operation is taking place in a hilly area, the bale may roll down a hill and could position the bale in a location where it would be difficult to retrieve. Furthermore, because, with varying crop conditions, the weight of the bale may vary from one bale to the next during the baling operation, the amount of energy imparted to the bale may need to be varied from one bale to the next. With the foregoing designs, such variation is not possible.
In U.S. Pat. No. 4,393,764 a cylindrical baler with a mechanism for moving a bale rearwardly of the discharge gate following discharge of the bale from the bale forming chamber is disclosed. The discharge gate includes at least a portion of the belts or chains which define the bale forming chamber and a pump for driving the belts or chains in a direction opposite to that used for bale formation. The gate is further operable to bring a portion of the belts or chains into contact with a discharged bale and to displace the bale rearwardly from the baler along the ground by imparting a controlled rearward rolling action to the bale. Such a baler provides a solution to many of the problems associated with the prior art balers discussed above. However, such a baler still suffers from certain limitations. For example, the belts defining the bale forming chamber must be tensioned in order to apply rolling action to the bale following discharge. Second, a mechanism for driving the belts in reverse must be provided. Third, the height of the gate must be properly adjusted so that the belts contact the bale. All of these requirements add complexity to the baler. In addition, if the baler is ejecting a bale on a hill with the baler headed downhill, the bale may not be moved entirely free of the gate due to the tendency of the bale to roll toward the baler.
Many round baler ejection devices include push bar devices to displace the bale clear from the path of the gate. A push bar device is disclosed in U.S. Pat. No. 4,483,247 wherein a cylindrical baler has a bale discharge ejector movable between a retracted position and an extended position. In the retracted position, the ejector is engageable with a bale discharged on the ground underneath a bale discharge gate of the baler and is operable to move the bale rearwardly of the gate as the ejector is moved to its extended position. The ejector is retained in the extended position while the gate is closed to insure that the bale remains clear of the gate during closing. U.S. Pat. No. 4,779,527 also discloses a push bar device wherein a U-shaped bale push bar straddles a discharge gate of a large round baler with opposite legs of the bar being respectively pivotally connected to a pair of support brackets secured to and projecting rearwardly alongside the discharge gate from upper rear locations of opposite sidewall sections forming a portion of the baler main frame. A pair of chains are coupled between forward locations of the gate and the legs of the push bar and serve as lost-motion connections that cause the push bar to extend and retract respectively in following relationships to opening and closing movements of the gate such that interference between the gate and a discharged bale is avoided. An over center spring assembly acts between the push bar and support brackets to bias the bar toward its retracted position when the gate is closed and to bias the push bar toward its extended position when the gate moves a small amount towards its open position a small amount beyond an intermediate position permitting discharge of a bale. Such devices still tend to cause excessive rolling of the bale; contributing to instability on hills, unrolling of twine and/or damage to wrapping materials.
Accordingly, there is a clear need in the art for a mechanism for producing a controlled discharge of a bale from a cylindrical baler that does not impart a rolling motion to the bale as it is discharged, thereby eliminating the problem of twine unwinding or damage to wrapping material.